Diagnostic Instructions

DTC Descriptors

DTC P040C: Exhaust Gas Recirculation (EGR) Temperature Sensor 1 Circuit Low Voltage

DTC P040D: Exhaust Gas Recirculation (EGR) Temperature Sensor 1 Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open	Short to Voltage
EGR Temperature Sensor 1 or EGR Temperature Sensor 2	P040C or P041C	P040D or P041D	P041D

Circuit/System Description

The engine control module (ECM) supplies 5 volts to the exhaust gas recirculation (EGR) cooler exhaust gas temperature sensor on the 5-volt reference circuit. The ECM also provides a ground on the low reference circuit. The EGR cooler exhaust gas temperature sensor provides a signal to the ECM on the EGR cooler exhaust gas temperature signal circuit, which is relative to the pressure changes in the manifold. The ECM should detect a low signal voltage at a EGR cooler exhaust gas temperature, such as low engine load. The ECM should detect high signal voltage at a high EGR cooler exhaust gas temperature, such as high engine load. The ECM monitors the EGR cooler exhaust gas temperature sensor signal for voltage outside the normal range of the EGR cooler exhaust gas temperature sensor.

Conditions for Running the DTC

P040C

P040D

Conditions for Setting the DTC

P040C

The ECM detects that the EGR cooler exhaust gas temperature sensor signal voltage is less than 0.1 volts.

P040D

The ECM detects that the EGR cooler exhaust gas temperature sensor signal voltage is more than 4.9 volts.

Action Taken When the DTC Sets

DTCs P040C and P040D are Type A DTCs.

Conditions for Clearing the DTC

DTCs P040C and P040D are Type A DTCs.

Diagnostic Aids

Inspect for any recent engine mechanical repairs. An incorrectly installed EGR sensor will cause this DTC to set.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Circuit/System Verification

Verify the integrity of the EGR sensor by inspecting for the following conditions:

Circuit/System Testing

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the harness connector at the EGR gas temperature sensor.
2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal A and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the control module.

3. Ignition ON, verify the scan tool EGR gas temperature parameter is more than 950°C (1742°F).

⇒	If greater than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the control module.

4. Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool EGR gas temperature parameter is less than 0°C (32°F) .

⇒	If voltage is less than the specified range, test the valve position drive circuits circuit for an open/high resistance. If the circuit tests normal, replace the control module.

⇒	If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the control module.

⇒	If all circuits test normal, replace the EGR gas temperature sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.